Gear-cutting machine.



l Ir. I". ROBERTS.

GEAR CUTTING MACHINE.

.IRRIGATION FILED 00T.15 1912.

.Patented Aug. 25),.1914..

Q W@ MJ@ @www 2 SHEETS-SHEET 1I Arromeys @im @um WITNESS/ES E. F. ROBERTS. GEAR. GUTING MACHINE. APPLICATION HLED OGT.15191`2.

Patented Aug. 25, 1914.

WITNESS/E5 EDWARD F. ROBERTS, OF DETROT, MICHIGAN, ASSIGNOIR.

LEO PACKARD MOIUR CAB,

i ooivrranv, or DETROIT, Mronronn, .a conronarron 'or 1i/Ironman.

enen-curative ifraenrnn.

incassa,

`Specification of Letters Patent. Patent/@dl hin-lg. 25, 119114.

application niet october i5, 1912. serial no. 725,954.

T0 all whom it may concern:

Be it known that l, EDWARD F. ROBERTS, a citizen of the United States, and resident of Detroit, Wayne county, 'State of Michigan, have invented certain new and useful lm; provements in Gear-Cutting Machines, ot which the following is a specification.

rihis invention relates to gear cutting inachincs and particularly to improvements in the type of machine described 'in Patents dated March 11, 1884, and 665,054, dated January 1, 1901. Both of said patents relate to machines for cutting gears of the bevel type, on what is called in the earlier of said patents the principle of evolution. These patents, however, are limited to the theory of, and machines for, cutting true bevel gears as distinguished from skew bevels or gears having curved or irregularly shaped teeth;

An object of the present invention is to render machines of this type capable of readilyv cutting skewed teeth in bevel gears, or curved or other teeth, which necessitates the tool passing diagonally across the face of the gear blank during the cutting opera-` tion.

Other objects of the invention will appear from the -vvfollowing' description, taken in connection with the drawings which orm a part of this specification, and in which,

Figure 1 is a side elevation and Vpart'section of a machine embodying the invention;

Fig. 2 is a plan view of the same; and- Fig..

3 'is an enlarged vertical sectional view of the head portion of the rain and the parts mounted thereon. Y n

Gear cutting machines of the type described in said patents usually comprise-a frame or base portion with blank holding and operating` mechanism mounted at one end of the frame and tool holding and op-v erating mechanism mounted at the other end.

of the trame. These two mechanisms are so associated .and timed in their operation that the blank is properly held in position for the tool to work upon it, the tool is lifted' on its return stroke, during which periodthe blank is properly spaced from' one tooth to another to allow the tool to operate upon the teeth consecutively, and the blank holding means is bodily rolled upon its former-cone for the purpose of generating the curved :tace of t-he tooth. ln the present invention it is intended that the blank holding and op- 4sized gears or blanks.A The blank erating mechanism and the tool holding and operating mechanism shall be so arranged Ythat one may be adjusted to an angular position relative to the other. As an illustration et one way to accomplish this purpose, l have shown in the drawings the tool holding and operating mechanism as mounted upon a support which is .adapted to oseii.

late about a vertical pivot arranged adiacent the geometric center of the machine. l

This form of the machine will now be described.

The frame or bed of the machine is indicated at 20,'and atthele't hand end shown in the gurs is mounted means for supper? mg and operating the gear blank. This supporting means consists principally oit a plate 21 mounted upon a dat upper surface 22 of the frame, and having a series of circular grooves 23 in which it the corresponding circular iianges 2d of a securing pla-te 25, which is fastened to the trame by the screws 26. The circumference of the plate 21 is formed' with gear teeth 27, with lwhich u meshes a worm 28 ldriven by a shaft 29, whereby the plate 21 is rotated or oscillated about a vertical axis which passes through the apex et the former-cone, hereinafter described. Y

The plate 21 carries two uprights 30 between which is adjustablyheld a block or bearing 31, as byl bolts 32. Thus this bear Ving is adjustable about the apex ofY the former-cone for operation upon diiiierent 33 is removably clamped to the arbor 34 which operates in the bearing 31, and upon the upper end of the arbor is rotatably mounted.

the housing 35 ofthe spacing head, the lower part of this housing comprising the formencone 36, which is a production of the pitch cone of the blank 33. By means of two steel bands 37, eaclrof which has one end attached to the cone 36 vand the other to the body of the machine in such a,way

' that one band prevents 'the sliding of the cone in one direction and the Vother in the other direction, the said cone being so' held that when the grooved plate 21 is oscillated, the cone will assume a vmotion as of a cone rolling on a plane without slip. It the housing 35, of which the said cone is a part, were coupled to the Ablank arbor 34, this vrolling motion would be transmitted to the blank 33, thereby imparting to the latter that mo- .Sap

soy

tion which is necessary to cause the tool to generate the proper tootli'contoui. j As a matter'of"fact,f;liowever, the housing 35 1s only intermittently coupled to the arbor v25a-namely, during the forward strokevof vthe tool. During the return stroke ofthe tool, the blank arbor isrotated in relationV to the housing through the distance, pref'- crably, of one tooth of the blank 33. This intermittent rotation is accomplished b a Imechanism for operating the cutting tool is mounted. Thei base or support 62 of this mechanism iS shown as resting on the frame in a circular 'groove or runway 63,-and may thus be moved about the axis of a pin 64, which is adjacent the lower end ofthe blank arbor 34, and which forms a connection betweenthe support 62 and the frame 20. The support may be secured in its adjusted position by meansof a set screw 65, and in Fig. 1 it is shown for convenience of illustration as 'secured in -its central position, while in Fig. 2 the support is adjusted to a diagonal position Yfor cutting skewed teeth. Y Upon the support 62 is a bearing 66v for the arbor or spindle 67 above referred to, which arbor carries a-driving pulley 68 having an ad-' justable crank69 thereon. By means of a connectingfrod'70 this 'crank is connected with a; ram 71, having a Vtool operating head 72 at its*` forward end.` For operating the spacing-mechanism at the left hand end of the machine, the driving pulley 68 carries a gear wheel 73 which engages with a pinion 7 4; mounted in an 'arm 75 extending from the bearing 66. This inion 74 is coupled to a ing mechanism referred to. l

It `will of course be understood that the ram 71 'slides .longitudinally in' suitable ways 4inthesupport 62'- The tool operating vhead 72- is formed vwith la horizontal dovetail groove 84, anda tool support 85 has a dovetail 86 fitting said'groove, whereby the tool support may slide transversely of the longi- -tudinal axis of the ram. An apron 87 is pivoted on the ,support 85 by a pin 88, and a tool holder 89 isadjustably secured to the front face of the apron. The securing means for the tool holder comprises a block' cutter 96, which is adapted to traverse the face of the gear blank 33 land cut the spaces v lbetween the teeth in thawellknown man- -n er:l 'Fori the', purpose gofy'fj'cuttingi "curved teeth or teeth firegularshape,the tool I support 85 may be connected with means for sliding it transversely of the longitudinal axis of the ram 71 simultaneously with the,

reciprocation of said ram. Asshown in the" drawings, this means consists of an arm 97 .secured to the' tool support 85, as shown'in Figs. 1 and 2,- and having a pin or roller 98.

adapted to operate in a cam slot 99- in a cam plate 100, which is secured preferably to the support 62 or other part of the machine j frame; AThe cam slot 99 may be of any de-r sired shape, but for thepurpose of cutting- .curved teeth said slot is 1n the form of an arc, as shown particularly in Fig.2. From the above description, it will be seen lthat as the ram 71 reciprocates through the medium of the connecting rod 70 and crank 69, the head 72 is carried with it, and the tool support. 85 in moving forwardly 1s guided. bythe" cam slot '99, rand caused to 'slide transversely in the head 72 simultaneously with its forward movement. On the return stroke of the ram,-the tool support 85 is of course caused to reverse its slid-A ing movement in the head 72, and the parts are returned to initial position. This combined forward and transverse movement of the tool support 85, 'by reason of the'curved cam slot 99, causes the tool 96 to move back and forth across the face of theA gear blank.

in a curvedl path'j-which is substantially Aparallel to a plane tangent to the pitch cone,

lthus cutting a' curved `space betweenl thev teeth, instead of a straight one as it would do without the cam mechanism. yIt will be v observed that the support 62 is movable parallel to the aforesaid'tangent plane and the adjustment of this support varies the :amount of angularity orl skewing of the teeth. as above described, 1 A

It is desirable to raise the tool during its return stroke so that' the blank may be rotated for a cut on the next-tooth, and for this purpose the apron 87 isfprovided 'withl an oset arm 103, on the end of which-is mountedalong roller 104. VAn a'r1'1i1105 extending` from .the support 62 has alever 106 pivoted at 107, and said lever is provided with a roller 108, which operates in an irregular jcam slotl 109 in the face of the pulley 68,

so that `the forward end of the lever 106V' depresses the arm 103 as it contacts with iis the roller 104C. The i'olleris made sufli" cient-ly long to be operated'upon by the lever 106 at any time duringthe transverse reciprocation of the tool support 85.` y By the action of this lever 106, the to'ol is alter` nately raised and'lowered, the cam slot-109 being so time'dth'at the toolwill be raised during the returnstroke and will be in its normal cutting position during its forward Agear are of coursecurved` inthe opposite direction to the teeth of the other. lThere-fp @surface of the blank, said tool operating stroke. The tool and apron are shown in cutting position in Fig. l, and in raised position as they lwould appear onthe return stroke y,in FigJS. .v

'In a pairof bevel gearsthe teeth of one fore it is 'desirable` to make the cam plate lOOvreversible so that 'a single cam may be used for cutting bevel y gears of a pair. In preparing the machine for the reverse cut,

Y besides reversing the cam, the support 62 is oscillated about the pin Gitothe opposite position at the other side 'of thev geometric l ce'nter X of' the machine. j,

It is believed that the operation of the machine Will be clearly understood from the above description, taken in connection with the tivo patents above referred to.

It will be understood that the invention is not limited to the specic form of the Inachine shown herein, but is capable of modification in various Ways Without departing from the scope of the claims.

Having thus described my invention, what I claim and desire to secure by Letters Patent, is

l. In a gear cutting machine, the combination with the bed thereof and formercone, of a support adjustably mounted on said bed and arranged to be bodily moved about an axis perpendicular to the plane. upon which the former-eolie rolls, blank holding and operating mechanism including vsaid former-cone and the A'surface upon which it rolls, and tool holding and operat-4 ing mechanism, one of said mechanisms being mounted on said adjustable support and the other said mechanism being mounted o-n said bed.

Zfllrn a gear cutting machine, the combi-.. nation with the bed thereof, and means for holding the blank, of a support for the tool operating mechanism adjustably mounted on said bed, and arranged to be bodily moved about va vertical axis adjacent the blank, a vtool operating'head mounted on said supportto reciprocate substantially in a plane across the acefof the blank, a tool support mounted to slide in the head,nieans ior reciprocating the head, and means for simultaneously sliding the tool support.

3. In a gear cutting machine, the combi- I nation with the bed thereof, and means mounted on said bed for holding the blank, of tool holding and operating mechanism mounted on the bed, and means permitting adjustment of the tool holdingmechanism, relative to the blank holding mechanism, arallel to a plane which is tangent tothe mechanism comprisingmeans for operating the tool in a curved path acre-ss the face of the blank.

4. In a gear cutting machine, the combination with the bed, and blank holding and operating mechanism mounted thereon, of a tool supporting head mounted for reciprocation on said bed, means for operating said head, means permitting adjustment of the part ot said bed supporting the head relativeto the blank holding mechanism, and means for causing a relative movement betvveen the blank and the tool in a horizontal plane but transversely to the reciprocating movement of the head and simultaneously With the latter movement.v

5. lin a machine :tor cuttingv bevel gears,. in combination, the bed or frame, means` nation,- means for holding and feeding the gear blank, a tool holding and operating mechanism comprising means for moving,

the tool in a curved-path across tlie face of the blank and substantially parallel to a plane tangent to the conical pitch surface of the blank, and means permittingtheradjustment of said tool holding mechanism relative to said blank holding means substantially parallel to said tangent plane.

ln testimony whereof I affix my signature in presence of two Witnesses.

EDVYARD F. ROBERTS. l/Vitnesses:

HOWARD B. Sermons, FREDERICK ROBERT `RoniNsoN. 

